Завдання 1403 - 1500 » 1462

Обчисли: 1) – 4/9 + (–5/12) = – (16 + 15)/36 = – 31/36; 2) 31/4 + (–41/8) = –(39/8 – 31/4) = – 7/8; 3) – 4/7 – 1 = – 4/7 – 7/7 = – 11/7 = –14/7; 4) 11/3 – (–21/6) = 11/3 + 21/6 = 33/6 = 31/2; 5) – 5/9 · (–18/25) = (5 ∙ 18)/(9 ∙ 25)) = 2/5; 6) 21/3 · (–42/7) = – (7 ∙ 30)/(3 ∙ 7) = –10; 7) – 12/13 : (–24/65) = (12 ∙ 65)/(13 ∙ 24) = 5/2 = 21/2; 8) – 15/16 : (–5) = 15/(16 ∙ 5) = 3/16.